textproduct: Rapid City

KEY MESSAGES

- Another round of severe thunderstorms is expected Thursday afternoon and evening with primary risks of large hail and damaging winds, although a tornado cannot be ruled out.

- Warming temperatures expected into the weekend.

UPDATE

Issued at 1030 PM MDT Wed Jun 3 2026

Made minor tweaks and adjustments to PoPs/QPF tomorrow, otherwise no major forecast changes were made with this evening's update. All-hazard severe weather threat remains, with solid shear and instability values supporting supercell structures with potential for very large hail, a tornado or two, and an increasing risk of damaging winds with time/eastward extent. CAMs don't offer great agreement on timing and evolution of storms, but we do think convective initiation may occur an hour or two earlier than some CAMs are showing over the Black Hills (aided by the terrain influence), possibly as early as 1 PM.

DISCUSSION

(This Evening Through Wednesday) Issued at 1250 PM MDT Wed Jun 3 2026

Visible satellite shows cloud cover over much of western SD with ongoing storms over north central SD. Skies have cleared out over Wyoming and the Black Hills with water vapor imagery showing narrow plume of mid level moisture streaming into south central SD. Sfc cold front makes its way across the eastern tier of the CWA through this afternoon and evening. Plume of 50-60F dewpoints and moderate instability of 2000-3000 J/kg SB CAPE will support thunderstorm development along the front. Mid-level flow will strengthen as the shortwave approaches with deep layer shear increasing to 30-40 kts which will support organized convection and rotating updrafts. CAMs are once again struggling with timing and storm mode with the HRRR continuing to push back development over south central SD until later this evening (after 6 to 7 pm) while the NAM and RRFS both show storms developing somewhat earlier (around the 4 to 5 pm MDT timeframe). Storms may start off as discrete cells, capable of large hail, damaging winds, and a low tornado risk. Storms will quickly coalesce into a line as the front pushes through with the primary threat transitioning to damaging wind gusts.

Attention turns to tomorrow where severe thunderstorms are once again possible across much of the forecast area. Another shortwave moving along nearly zonal flow will eject over the Northern Plains by the afternoon hours. Strengthening mid level flow will support deep layer shear values of 30 to 40 kts with SBCAPE values climbing to 2000-3000+ J/kg with the highest values across southwestern SD. This looks to be a typical northern Black Hills supercell environment, capable of very large hail (2+"), though a tornado or two can't be entirely ruled out. As storms push eastward over the plains through the evening hours, they may transition into an MCS with associated severe wind threat.

Things settle down for most of the CWA Friday as shortwave ridging builds to our west. Storms are still possible over south- central SD as the sfc front and shortwave exit the region. In addition, diurnally driven showers can't be ruled out over the Black Hills in the afternoon. Shortwave ridge will move over the region by Saturday and bring hot and dry conditions to the CWA. Storm chances return Sunday as upper level trof deepens over the western US and places our CWA under unsettled southwest flow.

AVIATION

(For the 06Z TAFS Through 06Z Thursday Night) Issued At 1045 PM MDT Wed Jun 3 2026

Light, moist easterly flow up against the Black Hills tonight into Thursday morning may support some form of low stratus and/or fog across portions of the South Dakota plains and southeastern foothills, especially between 10-16z.

Thursday afternoon, conditions then become favorable for isolated to scattered, potentially severe thunderstorms to develop over the Black Hills, western South Dakota plains, and northeastern Wyoming. Expect initiation after 18-20z, favored over the higher terrain of the Black Hills into southeast Montana. Large hail; frequent lightning; and gusty, erratic winds can be expected with any stronger convective cores. Transient MVFR/IFR conditions also expected around any heavier precipitation cores.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.